O2 sensor feedback flag

Matt · Post by **Matt** » Fri Aug 17, 2007 12:42 am

I'm having some fun (!) with the O2 sensor flag settings. I have found for the VG30 and SR20 at least that the O2 flag cannot be cleared when the AFR is between 29.4-14.82 (lean)

Tried this out on the bench and monitored the injector settings in consult whilst changing the values. Confirms what I see. Also noted that LiveEdit will screw up the values when below 14.7 and attempting to turn off O2 sensor flag

In this case when tuning you must either disable the O2 feedback flag or disconnect the sensor.

I'm going to fix the code so it only allows change the flag between 14.7-9.90

O2 FLAG CLEAR:
AFR Range 14.7 - 7.38 [0x00 - 0x7F]

O2 FLAG SET:
AFR Range 29.4 - 9.90 [0x80 - 0xFF]

Fusion Ed · Post by **Fusion Ed** » Fri Aug 17, 2007 4:29 am

So matt, do you mean if you have AFR on a load cell that's greater than 14.7 the sensor O2 is always active regardless of weather that cell is flagged or not?

Matt · Post by **Matt** » Fri Aug 17, 2007 5:39 pm

Any cell with 14.7 or greater cannot have the O2 sensor flag turned off on it

There is no raw value to translate it back to in the ECU.

So the next version of NIStune wont let you turn it off. Previous versions may have let you but put the cell value to an incorrect raw number

Fusion Ed · Post by **Fusion Ed** » Sat Aug 18, 2007 4:31 am

interesting, that i wasn't aware of. Ok well it shouldn't in theory matter as long as the fuel table agrees with whats going on in real life.
In every case so far where I have had around 14.7, I would want o2 feedback anyway.

Lucius · Post by **Lucius** » Fri Oct 26, 2007 3:12 pm

Not sure if this is relevant to this particular case, but my tuner and i found that we needed to disconnect the o2 sensor when tuning my SR20 as for some reason with the o2 sensor plugged in the car would run much richer no matter how much the fuel maps were adjusted.

Is there anything that can be done to stop this from happening or have we missed something?

Tune is perfect with the o2 sensor unplugged.

Matt · Post by **Matt** » Fri Oct 26, 2007 3:43 pm

There is a 'O2 feedback flag' in the constants list

This parameter has a series of tickboxes. One of them you untick and turns it off. Think it was 'bit7' but need to check

SSS · Post by **SSS** » Sun Oct 28, 2007 6:57 pm

Has this been implemented for the KA24E stuff yet matt? I'm sure gabe would have input in this?

Matt · Post by **Matt** » Mon Oct 29, 2007 1:04 am

Yes if you have the 'O2 feedback' flag

For S13 KA24E is
FB_SWITCH,&H0038,1,1,1,1,Feedback control

Then it will work in latest test release version at least anyway

On the topic of KA24E I've got a USDM KA24E ECU... thought they were the same as the ADM ones.

Not so sure about that now. All the consult parameters which I worked out for your ECU appear to be different in the USDM ECU

So have to work them all out again...

Lucius · Post by **Lucius** » Mon Oct 29, 2007 10:30 am

Thanks Matt, will give it a go and let you know.

CGTuning · Post by **CGTuning** » Thu Nov 01, 2007 2:52 am

matt, i always tune with o2 feedback OFF, with the new version of nistune, which check boxes does this? i see Bit0 thru Bit7

Matt · Post by **Matt** » Thu Nov 01, 2007 5:13 pm

Yes they do. I've just done some research on this and looked into the ECU code

There seems to be two different meanings to the same parameter...

See my post at the bottom of this thread
http://ecu2.forumwise.com/ecu2-post-11103.html#11103

Basically 8 bit ECUs (R32/Z32 etc) are a value in degrees - 50 which the O2 feedback activates

16 bit ECUs use the top 3 flags (bits 5,6,7) for O2 feedback. Turning these OFF should prevent O2 feedback. We dont know how exactly they are used though

I'm going to have to split the address file up from FB_SWITCH to FB_TEMP for the 8 bit ECUs so this is interpreted differently.

Enhancement to be added for this item